1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to an image processing apparatus and a control method thereof, and more particularly, to an image processing apparatus which performs dithering to output an image of high-quality, and a control method thereof.
2. Description of the Related Art
Generally, an image processing apparatus such as a plasma display panel (PDP) device processes an image signal such as a broadcasting signal to display an image thereon. While processing R, G and B image signals, the image processing apparatus applies a de-gamma compensation to the image signals to improve brightness.
In this case, a noise occurs in a low gray scale, and deteriorates image quality. Thus, the image processing apparatus performs dithering to prevent deterioration of the image quality. Dithering is used to reduce false contour by adding noise properly to a gray scale of an image to be displayed.
Hereinafter, a dithering method of a related art image processing apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a control block diagram of the related art image processing apparatus. As shown therein, the related art image processing apparatus includes a signal input unit 1, a random generator 2, a line buffer 3, a frame buffer 4, a dithering performer 5 and a display unit 6.
The random generator 2 generates a random value to determine a mask seed value of respective frames in an image input by the signal input unit 1. Here, the random generator 2 generates the random value in every M×N positions of the respective pixels with position information of the pixels displaying the image, and generates the mask seed value corresponding thereto.
The mask seed value is used to perform dithering by the dithering performer 5 (to be described later), and to determine a mask matrix corresponding to the concerned mask seed value in the respective pixel positions.
The identical mask seed value is used during one period in the related art image processing apparatus. Thus, the mask seed value generated by the random generator 2 is stored during the one period. In this case, the single period includes at least one line and at least one frame.
As shown in FIG. 2, a mask seed value per line (8a, 8b) is stored in the line buffer 3 while a mask seed value of plural lines corresponding to a single frame (8a, 8b, 8c, 8d) is stored in the frame buffer 4. As the period changes, the random generator 2 generates a new random seed value. A new mask seed value is also stored in the line buffer 3 and/or the frame buffer 4.
The dithering performer 5 determines the mask matrix corresponding to the position of the pixel by using the mask seed value stored in the line buffer 3 and the frame buffer 4, and performs dithering with the determined mask matrix. That is, the dithering performer 5 adds the determined mask matrix values to input images r, g and b, and adjusts bits corresponding to an output standard to output images r′, g′ and b′ having improved image quality. Then, the display unit 6 displays the images with improved quality.
To perform dithering by the related art image processing apparatus, however, the mask seed value which is generated by the random generator 2 should be stored in the line buffer 3 and frame buffer 4. That is, the related art image processing apparatus requires the line buffer 3 and the frame buffer 4, which raises production costs.